Method and apparatus for highly effective on-chip quantum random number generator

ABSTRACT

A true random number generator is presented that includes a CMOS matrix detector with a top surface. A shell is positioned over the top surface, and the shell includes a radiation source and a luminophore or scintillator constructed to emit photons towards the top surface when the luminophore or scintillator is struck by electrons from the radioactive decay of the source of the radiation. The CMOS detector matrix is constructed to detect the photons emitted from the luminophore or scintillator and to produce a signal for the detected photons. The signal is communicated to a processor that produces true random numbers based on the signal from the detected photons.

PRIORITY APPLICATIONS AND REFERENCES Technical Field

The present disclosure relates generally to true random numbergenerators, and more specifically to random number generatortechnologies utilizing the spontaneous Nickel isotope decay, as well asapparatus, systems, and methods regarding same.

This application claims priority to U.S. Provisional Application Ser.No. 63/344,496 titled “Method and Apparatus for Highly Effective On-ChipQuantum Random Number Generator” filed on May 20, 2022; to U.S.Provisional Application Ser. 63/279,587 titled “Method forCost-Effective Nickel-63 Radiation Source for True Random NumberGenerators” filed on Nov. 15, 2021; to U.S. Provisional Application Ser.63/277,759 titled “Method for Cost-Effective Nickel-63 Radiation Sourcefor True Random Number Generators” filed on Nov. 10, 2021; to U.S.Provisional Application Ser. 63/224,811 titled “Method And Apparatus ForHighly Effective Beta Decay Based On-Chip True Random Number Generator”filed on Jul. 22, 2021; to U.S. Provisional Application Ser. 63/234,820titled “Method And Apparatus For Highly Effective Beta Decay BasedOn-Chip True Random Number Generator” filed on Aug. 19, 2021; to U.S.Provisional Application Ser. 63/235,031 titled “Method And Apparatus ForHighly Effective Beta Decay Based On-Chip True Random Number Generator”filed on Aug. 19, 2021; and to U.S. Provisional Application Ser.63/270,912 titled “Method And Apparatus For True Random Number GeneratorBased On Nuclear Radiation” filed on Oct. 22, 2021, all of which areincorporated herein by reference in their entireties.

This application is also related to U.S. application Ser. No. 17/687,630titled “Method for Making Cost-Effective Nickel-63 Radiation Source forTrue Random Number Generators” filed on Mar. 5, 2022; to U.S.application Ser. No. 17/513,661 titled “Method And Apparatus For HighlyEffective Beta Decay Based On-Chip True Random Number Generator” filedon Oct. 28, 2021; to U.S. application Ser. No. 17/409,971 titled “MethodAnd Apparatus For Highly Effective On-Chip True Random Number GeneratorUtilizing Beta Decay” filed on Aug. 24, 2021; to U.S. ProvisionalApplication Ser. 62/984,528 titled “Method And Apparatus ForTritium-Based True Random Number Generator” filed on Mar. 3, 2020; toU.S. Provisional Application Ser. 63/062,672 titled “Method AndApparatus For Beta Decay Based True Random Generator” filed on Aug. 7,2020; to U.S. Provisional Application Ser. 62/655,172 titled “Apparatus,Systems, And Methods Comprising Tritium Random Number Generator” filedon Apr. 9, 2018; to U.S. Provisional Application Ser. 62/803,476 titled“Apparatus, Systems, And Methods Comprising Tritium Random NumberGenerator” filed on Feb. 9, 2019, now U.S. Pat. No. 10,430,161; to U.S.application Ser. No. 16/273,365 titled “Apparatus, Systems, And MethodsComprising Tritium Random Number Generator” filed on Feb. 12, 2019; toU.S. application Ser. No. 16/990,087 titled “Apparatus, Systems, AndMethods For Beta Decay Based True Random Number Generator” filed on Aug.11, 2020, now U.S. Pat. No. 10,901,695; to U.S. application Ser. No.17/126,265 titled “Method and Apparatus for Tritium-based True RandomNumber Generator” filed on Dec. 18, 2020, now U.S. Pat. No. 11,048,478;to U.S. application Ser. No. 17/062,307 titled “Apparatus, Systems, AndMethods For Beta Decay Based True Random Number Generator” filed on Oct.2, 2020, now U.S. Pat. No. 11,036,473; to PCT Application SNPCT/US19/17748 titled “Apparatus, Systems, And Methods ComprisingTritium Random Number Generator” filed on Feb. 13, 2019; to PCTApplication SN PCT/US20/65962 titled “Apparatus, Systems, And MethodsFor Beta Decay Based True Random Number Generator” filed on Dec. 18,2020; and to PCT Application SNPCT/US20/65976 titled “Apparatus,Systems, And Methods For Beta Decay Based True Random Number Generator”filed on Dec. 18, 2020. Each of the patent applications, issued patents,and other references discussed and/or cited herein, are incorporated byreference as if fully set forth herein.

BACKGROUND

As opposed to pseudo-random number generators based on numericalalgorithms, there are true random number generator (TRNG) devices thatdepend on natural random processes: multiple bipolar switches, thermalnoise, light scattering by dichroic mirrors, chaotic systems, and decayof radioactive nuclei. Some of these TRNGs are listed in the provisionalapplications to which the present application claims priority, and thosereferences are incorporated herein by reference as if fully set forthherein.

The decay of radioactive nuclei type is considered to be the mostindependent from environmental influences like temperature, pressure, oracceleration. However, typical nuclear-based TRNGs require large sizedetectors to enable the registration of particles emitted as a result ofradioactive decays. Also, many nuclei used in such devices are highlyradioactive and poisonous, hence dangerous to humans if a device isbroken.

In previous disclosures by the present inventors, a TRNG is disclosed.For example, U.S. Pat. No. 10,901,695 entitled “Apparatus, systems, andmethods for beta decay based true random number generator”, an array ofdetectors was employed and a method of adjusting counts by changing theread-out time was described. The contents of that patent areincorporated herein by reference. The source of entropy in the '695patent was a thin layer of Nickel-63 attached to the inner surface ofthe metallic cover of the package of the integrated circuit (IC).Likewise, in U.S. Pat. No. 11,281,432 entitled “Method and apparatus fortrue random number generator based on nuclear radiation”, an array ofdetectors was employed to detect electrons (i.e., entropy) from theradiation source. Further, the '432 patent disclosed a method ofadjusting the counting rates of these detectors based on the varyingdiameter of their surface. The disclosed method is very effective incompensating for the limited (finite area) of the radiation source.However, designing and manufacturing such a detector array iscomplicated because typical electrical parameters of a single diode varyconsiderably with the area. The contents of both the '695 and '432patents are incorporated herein by reference.

A solution might be to create a source of electrons that produces a veryuniform flux through a given surface. The problem is well known inclassical optics: using a single point source and a paraboloidal mirrorone can produce the required uniform flux, an example of which is atypical automobile front headlight. Unfortunately, creating a pointsource of electrons or a mirror that reflects these electrons is not aneasy task, especially if such a device should be mounted inside anintegrated chip. The most obvious solution, i.e., placing the radiationsource just over the detectors, could be not a practical one because ofthe sensitivity of the surface for any contaminants as well as for themechanical separation needed if the radiation source is deposited on theenclosure to allow for temperature expansion. If there is a gap betweendetectors and the source, then outer pixels will not receive the sameelectron flux as those inside the matrix.

Therefore, a cost-effective method for making a radiation source in aTRNG with a more uniform flux would be advantageous. Such a TRNG canthen be used in compact personal devices.

SUMMARY

In a first embodiment, a true random number generator is presented thatincludes a CMOS matrix detector with a top surface. A shell ispositioned over the top surface, and the shell includes a radiationsource and a luminophore or scintillator constructed to emit photonstowards the top surface when the luminophore or scintillator is struckby electrons from the radioactive decay of the source of the radiation.The CMOS detector matrix is constructed to detect the photons emittedfrom the luminophore or scintillator and to produce a signal for thedetected photons. The signal is communicated to a processor thatproduces true random numbers based on the signal from the detectedphotons. The shell may also include a material such as metal to blockthe emission of radioactive decay from escaping the TRNG. The shell mayinclude three layers; the first layer comprises the luminophore orscintillator, the second layer comprises the radiation source, and thethird layer comprises the material to block the emission of radioactivedecay from the radiation source. The first layer is positioned closestto the top surface 16, and the third layer is positioned farthest fromthe top surface 16. The luminophore or scintillator may be comprised ofNaI(TI), and the shell may be a half-dome.

In a second embodiment, a true random number generator (TRNG) ispresented that includes a CMOS matrix detector with a top surface. Ahalf-dome shell is positioned over the top surface, and the shellincludes a first layer comprising a radiation source and a second layercomprising a material (such as metal) to block the emission ofradioactive decay. The first layer is positioned closest to the topsurface, and the second layer is positioned farthest from the topsurface. The CMOS matrix detector is constructed to detect electronsemitted from the decay of the radioactive source and to produce a signalfor the detected photons. The signal is communicated to a processor thatproduces true random numbers based on the signal from the detectedphotons.

In either embodiment, the TRNG may have a radioactive source ofNickel-63, and the detector may be comprised of an array of detectors.Either embodiment may be integrated into a self-contained microchip.

Additional aspects, alternatives, and variations as would be apparent topersons of skill in the art are also disclosed herein and arespecifically contemplated as included as part of the invention. Theinvention is set forth only in the claims as allowed by the patentoffice in this or related applications, and the following summarydescriptions of certain examples are not in any way to limit, define orotherwise establish the scope of legal protection.

BRIEF DESCRIPTION OF DRAWINGS

The invention can be better understood with reference to the followingfigures. The components within the figures are not necessarily to scale,emphasis instead being placed on clearly illustrating example aspects ofthe invention. In the figures, like reference numerals designatecorresponding parts throughout the different views and/or embodiments.Furthermore, various features of different disclosed embodiments can becombined to form additional embodiments, which are part of thisdisclosure. It will be understood that certain components and detailsmay not appear in the figures to assist in more clearly describing theinvention.

FIG. 1 illustrates the problem of calculating the path of electronsemitted from a point source.

FIG. 2A illustrates three different radiation sources A, B, and C thatare modeled in FIG. 2B.

FIG. 2B graphs the radiation flux across an array of detectors forradiation sources of A, B, and C in FIG. 2A.

FIG. 3A illustrates a half-sphere radiation source over a CMOS matrixtaken at the cross-section shown in line A-A of FIG. 5 .

FIG. 3B illustrates in greater detail the layers of the dome over theCMOS matrix.

FIG. 4A illustrates a half-sphere radiation source with aluminophore/scintillator over a CMOS matrix taken at the cross-sectionshown in line A-A of FIG. 5 .

FIG. 4B illustrates in greater detail the layers of the dome with aluminophore or scintillator over the CMOS matrix.

FIG. 5 illustrates a self-contained TRNG chip.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

Reference is made herein to some specific examples of the presentinvention, including any best modes contemplated by the inventor forcarrying out the invention. Examples of these specific embodiments areillustrated in the accompanying figures. While the invention isdescribed in conjunction with these specific embodiments, it will beunderstood that it is not intended to limit the invention to thedescribed or illustrated embodiments. On the contrary, it is intended tocover alternatives, modifications, and equivalents as may be includedwithin the spirit and scope of the invention as defined by the appendedclaims.

In the following description, numerous specific details are set forth inorder to provide a thorough understanding of the present invention.Particular example embodiments of the present invention may beimplemented without some or all of these specific details. In otherinstances, process operations well known to persons of skill in the arthave not been described in detail in order not to obscure unnecessarilythe present invention. Various techniques and mechanisms of the presentinvention will sometimes be described in singular form for clarity.However, it should be noted that some embodiments include multipleiterations of a technique or multiple mechanisms unless noted otherwise.Similarly, various steps of the methods shown and described herein arenot necessarily performed in the order indicated, or performed at all incertain embodiments. Accordingly, some implementations of the methodsdiscussed herein may include more or fewer steps than those shown ordescribed. Further, the techniques and mechanisms of the presentinvention will sometimes describe a connection, relationship, orcommunication between two or more entities. It should be noted that aconnection or relationship between entities does not necessarily mean adirect, unimpeded connection, as a variety of other entities orprocesses may reside or occur between any two entities. Consequently, anindicated connection does not necessarily mean a direct, unimpededconnection unless otherwise noted.

The following list of example features corresponds to the attachedfigures and is provided for ease of reference, where like referencenumerals designate corresponding features throughout the specificationand figures:

Half-Sphere Cover 10 CMOS Matrix 15 Shell 20 Radiation Source 25Luminophore/scintillator 30 Self-Contained TRNG Chip 35 Area forAdditional Integrated Circuit Components 40 Processor 45

This is related to our previously published US patents and applicationslisted above, in which we described the general idea of using pure betaminus (electron emission) nuclear decay as a medium or source of entropyfor generating true random numbers by detecting emitted electronson-chip through an electronic sensor or array of sensors. In thisapplication, we present an approach to manufacturing the radiationsource to be used in the previously disclosed TRNGs, as a thin layerwithout handling concerns. The radioactive source may beelectro-deposited; ⁶³Ni is available in a solution as Nickel chloride.

Here we propose a design of a radiation source on some surface placedabove the array of the same detectors. FIG. 1 illustrates the problem ofcalculating the path of electrons emitted from point A into thedirection of the array of detectors (placed on the surface z=0) with theemission angle φ measured from the line being perpendicular to thesurface of the detectors' array. In general, such a problem in 3D wouldrequire complicated stereo geometrical expressions and integration overthe whole surface on which the radiation source is placed. By assumingrotational symmetry around the axis placed at x=r, this can besimplified, but the integration will still require the path integrals ofcomplicated trigonometric formulas, cf. e.g., our previous patents,which were the simplest case where a surface is just a plane placed atz=z₀. Instead of attempting to solve analytically these complicatedequations, a Monte Carlo simulation of a large number of particlesplaced at various, random positions on the plane (parameter x₀) andrandomly emitted at various angles φ was employed. The surface is givenas a function z(x), for example, a half-spherical one is defined by:

z=√{square root over (r ²−(x−r)²)}+h  (1)

where r is the radius of the sphere, h is the distance between thecenter of the sphere and the detectors' surface (h=0 if the half-spheresits on the surface as shown in FIG. 2A diagram Case A) while x∈[0;2r].The Monte Carlo simulation was performed and an expected, uniformdistribution across all the detectors for a spherical surface source wasobtained, cf. FIG. 2B, case A. The software allows easy replication ofthe results obtained analytically in the previous patent by setting:

z=h  (2)

Using the same simulations, data was obtained for an area of the sourceequal to the area of detectors. This structure is shown in FIG. 2Adiagram Case C, with the flux shown graphically in FIG. 2B, case C.

Assuming h>0, one can test the situation when the sphere is liftedslightly above the detector's surface. This structure is shown in FIG.2A diagram Case B, with the flux shown graphically in FIG. 2B, case B,which results fall in between the other simulations.

FIG. 3A (a cross-section taken at line A-A in FIG. 5 ) illustrates aTRNG that implements the more even electron flux produced by thehalf-dome. The TRNG includes a CMOS matrix detector 15 with a topsurface 16. A half-dome shell 10 is positioned over the top surface 16,and the shell 10 includes a first layer comprising a radiation source 25and a second layer comprising a material 20 (such as metal) to block theemission of radioactive decay, see FIG. 3A. The first layer ispositioned closest to the top surface 16, and the second layer ispositioned farthest from the top surface 16. The CMOS matrix detector 15is constructed to detect electrons emitted from the decay of theradioactive source 25 and to produce a signal for the photons to bedetected. The signal is communicated to a processor 45 (see FIG. 5 )that produces true random numbers based on the signal from the detectedphotons.

It is worth noting that to get accurate, smooth solutions to the problem(as shown in FIG. 2B), one has to generate a large number ofelectrons—for this simulation we used 100 million electrons.Interestingly, Visual Basic's intrinsic random number generator—theprogram used for the simulation—has a limited cycle of random numbers(it is an algorithmic generator) of only about 16·10⁶ different numbersfrom the range of [0,1]. Hence, we used the pseudo-random numbergenerator subroutine based on the Wichman-Hill algorithm (B. A. Wichmanand I. D. Hill An Efficient and Portable Pseudo-random Number Generator,Journal of the Royal Statistical Society Series C (Applied Statistics)Vol. 31, No. 2 (1982) pp. 188-190) that generates sequences of thelength of about 2.8·10¹³ numbers, i.e., large enough so not a singlenumber is being reused in any given software run. This practical exampleclearly shows that good random number generators should be a hardwarepart of any workstation so that users do not need to worry aboutimperfections of random numbers used.

Detecting electrons is slightly more complicated than detecting photons(different interactions with solid matter) so we propose anothermodification of the radiation source used in the described detector'smatrix-based random number generator. If the thin layer of the electronradiation source (in our case Nickel-63 source is thin because theself-absorption of electrons makes the thicker layer redundant) iscovered with a thin layer of a luminophore or other scintillationchemical (like widely used NaI(TI) coating), it can produce manythousands of photons in a visible light spectrum per single electroncaptured.

One possible construction is shown in FIG. 4A (a cross-section taken atline A-A in FIG. 5 ), where a half-sphere cover 10 is comprised of ashell 20, a radiation source 25 (e.g., Nickel-63), andluminophore/scintillator 30. This allows the use of a standard CMOSmatrix 15 of detectors available commercially with over 20 millionpixels and a readout time of less than 10 ms per frame (more than 100frames per second). This means that by comparing the numbers of photonsdetected by each pixel of a single frame with a median count (calculatedduring initialization of the system from the frequency histogram ofcounts), one can generate random bits at about 2 Gb/sec from the CMOSarray that covers not much more than 1 cm². The extraction of entropy issimple in this case: pixel counts lower than median mean zero, pixelcounts higher than median mean one. This is an ultimate high speed andhigh throughput quantum random number generator using an ultimateentropy source (beta decay) that cannot be influenced by anyenvironmental factors and does not change much with time.

The TRNG in FIG. 4A includes a CMOS matrix detector 15 with a topsurface 16. A shell 10 is positioned over the top surface 16, and thatshell 10 includes a radiation source 25 and a luminophore orscintillator 30 constructed to emit photons towards the top surface 16when the luminophore or scintillator 30 is struck by electrons from theradioactive decay of the source of the radiation 25. The CMOS detectormatrix 15 is constructed to detect the photons emitted from theluminophore or scintillator 30 and to produce a signal for the detectedphotons. The signal is communicated to a processor 45 (see FIG. 5 ) thatproduces true random numbers based on the signal from the detectedphotons. The shell 10 may also include a material 20 such as metal toblock the emission of radioactive decay from escaping the TRNG. Theshell, as shown in the detail in FIG. 4B, may include three layers; thefirst layer comprises the luminophore or scintillator 30, the secondlayer comprises the radiation source 25, and the third layer comprisesthe material 20 to block the emission of radioactive decay from theradiation source 25. The first layer is positioned closest to the topsurface 16, and the third layer is positioned farthest from the topsurface 16.

Even if traditional LED light sources can be placed inside a sphericaldome, they are still not stable over a long time. On the other hand,beta decays of Nickel-63 have a half-life time of about 100 years, whichmeans that the flux of electrons diminishes only by about 0.7% per year,which is over two orders of magnitude smaller than the flux itself.Also, a fluorophore or scintillator, although subject to radiationdamage, will last for more than 10 years of a practical lifetime of thedescribed high throughput random number generator. With about 10²²molecules of luminophore or scintillation chemical per mole in normalconditions, even if each electron will damage one molecule permanently,and with a flux of 10⁸ electrons impinging luminophore or scintillatorper second, after 10 years of irradiations (about 3·10⁸ seconds) therewill be still orders of magnitude more fresh molecules that will be ableto emit photons.

Most commercial CMOS matrices have a ratio of edges of about 9 to 16(the HD video format) which means that a spherical dome will leaveenough space on the sides of such a CMOS to be used for accompanyingICs, presumably manufactured on the very same piece of silicon so thewhole unit will be self-contained random number generatorsystem-on-chip. FIG. 5 illustrates a self-contained TRNG chip 35 withthe CMOS matrix 15 and areas 40 on both sides of the CMOS matrix 15 thatmay be used for additional IC components. One such component that may beincluded in the self-contained chip is a processor 45 that produces truerandom numbers based on the signal from the detector.

Let us do some estimates of the amounts of radiational source needed.Assuming matrix pixels size of 5 microns by 5 microns and the sourceplaced just on the matrix (no gap), one obtains about 140 electronshitting each pixel per second assuming 15 mCi surface activity. Thismeans that one can read out such a matrix at least 100 times per secondknowing that on average each pixel will be hit at least once. If thematrix can be only read less frequently, then the radiational source canbe thinner, thus producing fewer electrons per second which can beadvantageous because of the cost of Nickel-63. The same applies tolarger pixels, for example, 10 microns by 10 microns pixels will be hitby at least 550 electrons per second, etc. Since the area of thehalf-sphere as described above is about 2 times larger than the areacovered by the matric comparable with the area of the spherecross-section, the source can be even thinner.

Provided in the Appendix are calculations for the performance of theTRNG based on a new Canon SPAD sensor, seehttps://global.canon/en/news/2021/20211215.html. It is found that theCanon SPAD sensor can produce 0.27 GB/sec/cm². Thus, to obtain 2 GB/sec,a 10 cm² matrix is necessary (about 3.15 cm×3.15 cm or about 1.5 in.×1.5in. area). With a PCB having an area of 150 cm², one can achieve up to30 GB/sec provided that one can get consistent throughput throughout theinterface of PCB like PCI Express. Practically, it may be more effectiveto network several smaller PCBs if such a high throughput is necessary.

Any of the suitable technologies, materials, and designs set forth andincorporated herein may be used to implement various example aspects ofthe invention, as would be apparent to one of skill in the art.

Although exemplary embodiments and applications of the invention havebeen described herein including as described above and shown in theincluded example Figures, there is no intention that the invention islimited to these exemplary embodiments and applications or to how theexemplary embodiments and applications operate or are described herein.Indeed, many variations and modifications to the exemplary embodimentsare possible, as would be apparent to a person of ordinary skill in theart. The invention may include any device, structure, method, orfunctionality, as long as the resulting device, system, or method fallswithin the scope of one of the claims that are allowed by the patentoffice based on this or any related patent application.

1. A true random number generator (TRNG) comprising: a detector with a top surface; a shell position over the top surface, the shell comprising: a radiation source; and a luminophore or scintillator constructed to emit photons towards the top surface when the luminophore or scintillator is struck by electrons from the radioactive decay of the radiation source; wherein the detector is constructed to detect the photons emitted from the luminophore or scintillator, and to produce a signal for the detected photons; and a processor connected to the detector and constructed to produce true random numbers based on the signal from the detected photons.
 2. The TRNG of claim 1, wherein the radioactive source is Nickel-63.
 3. The TRNG of claim 1, wherein the luminophore or scintillator is comprised of NaI(TI).
 4. The TRNG of claim 1, wherein the detector comprises an array of detectors.
 5. The TRNG of claim 1, wherein the shell comprises a material to block the emission of radioactive decay.
 6. The TRNG of claim 1 wherein the shell comprises: a first layer comprising the luminophore or scintillator; a second layer comprising the radiation source; and a third layer comprising a material to block the emission of radioactive decay from the radiation source; wherein the first layer is positioned closest to the top surface, and the third layer is positioned farthest from the top surface.
 7. The TRNG of claim 1, wherein the shell is a half-dome.
 8. A self-contained microchip comprising the TRNG of claim
 1. 9. A true random number generator (TRNG) comprising: a detector with a top surface; a half-dome shell position over the top surface, the shell comprising: a first layer comprising a radiation source; and a second layer comprising a material to block the emission of radioactive decay; wherein the first layer is positioned closest to the top surface, and the second layer is positioned farthest from the top surface; wherein the detector is constructed to detect electrons emitted from the decay of the radioactive source, and to produce a signal for the detected photons; and a processor connected to the detector and constructed to produce true random numbers based on the signal from the detected photons.
 10. The TRNG of claim 1, wherein the radioactive source is Nickel-63.
 11. The TRNG of claim 1, wherein the detector comprises an array of detectors. 